In the process of xerography, a marking material such as toner is generally transferred to a substrate media sheet with the substrate media sheet then being transported to a fusing system for permanently binding the toner to the substrate media. The binding of toner particles on to the substrate media, which is typically referred to as fusing, generally demand that the toner carried by the substrate media remain untouched or undisturbed prior to the fusing stage. Accordingly, sheets of substrate media after receiving toner are generally transported immediately to a fuser over a very short media path in order to avoid any unwanted contact with the toner image.
In order to fuse toner onto a substrate media sheet, such as paper, xerographic printers typically incorporate a device called a fuser. While fusers can take many forms, heat or a combination of heat and pressure fusers are currently most common. Using a heat fusing roll in combination with an adjacent pressure roll is one example of such a combination fuser. Such combined rolls, typically applying pressures between 10 and 200 psi, cooperate to form a fusing nip through which the paper carrying toner passes. The heat at least partially melts the toner and the pressure helps force it to bind with the paper. Heat fusing generally requires temperatures above room temperature, reaching as high as 175 degrees Celsius. The lower end of that temperature range generally requires higher pressure be applied in addition to the heat.
Another technique of fusing is known as cold-pressure fixing. Cold-pressure fixing relies primarily on pressure to secure the toner to the substrate. In this way, cold-pressure fixing generally consists of squeezing a substrate sheet carrying toner between two solid rolls. While requiring pressure between the two rolls, cold-pressure fixing can generally be performed between 10-65 degrees Celsius, which includes temperatures at or near room temperature. In contrast, other forms of fusing require significantly higher levels of energy for generating heat. While, conventional cold-pressure fixing systems use a relatively high level of pressure in order to permanently fix the toner to the substrate media, the energy and or costs associated with the process is substantially less than that required for other fusing techniques. However, conventional cold-pressure fixing systems are also known for either significant smearing or adding an unintentional gloss, thus negatively affecting image resolution or quality.
FIG. 8 shows a tightly integrated parallel processing (TIPP) assembly 800 where toner is immediately fused to sheets of substrate media after each individual marking engine ME deposits toner thereon. As shown, individual subassemblies 802, 804, 806, 808 each include their own marking engine ME. The individual marking engines ME include very short media paths that immediately lead to an internal heating fuser 80. In this way, between the initial sheet feeder 7 and the eventual sheet finisher 9, the overall assembly 800 includes a plurality of high energy consuming heat fusing devices 80 in order to achieve its parallel processing. One reason for the individual heated fusers 80 is to relieve concerns with regard to images conveyed along the extensive sheet path 2 and across the numerous handling sensors 810 and rolls 820 within the greater assembly 800. However, such heated fusers 80 can be made to reach as high as 200 degrees Celsius. Thus, such high energy heat fusers 80 are not only a source of energy consumption, but also each have maintenance costs associated with them as well.
Accordingly, it would be desirable to provide an apparatus and method for handling substrate media in a marking device using toner that is efficient, cost effective and overcomes the various shortcomings of the prior art.